Vane pump with thrust absorber, floating rotor and balanced seal



G. P. KENNEDY VANE PUMP WITH THRUST ABSORBER, FLOATING July 16, 1968 ROTOR AND BALANCED SEAL 2 Sheets-Sheet 1 Filed Jan. 21, 1966 Fig.2

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AIM

United States Patent 3,392,677 VANE PUMP WITH THRUST ABSORBER, FLOAT- ING ROTOR AND BALANCED SEAL Garth P. Kennedy, Oklahoma City, Okla., assignor to Corken Pump Company, a corporation of Oklahoma Filed Jan. 21, 1966, Ser. No. 522,122 7 Claims. (Cl. 103-134) ABSTRACT OF THE DISCLOSURE A pump rotor is maintained in a floating condition by fluid under pressure within a pump chamber between side plates. Dimensional variations in the axial clearance between the rotor and the side plates does not affect the floating condition because of a thrust absorbing extension slidably mounted on the pump shaft through which torque is transmitted to the shaft and radial bearings independently journaling the shaft at locations spaced from the side plates by balanced seal assemblies.

This invention relates to pump units for extremely low viscosity fluids and more particularly to a fluid sealing and thrust absorbing bearing assembly for vane types of pumps.

In connection with the pumping of low viscosity fluids such as propane, ammonia, etc. extremely close tolerances are required for the clearance or gap between the pump rotor and the side plates enclosing the pump chamber. Any significant variation in such gap either causes a substantial reduction in the capacity of the pump or seizure between the confronting surfaces of the rotor and the side plates. Aside from the problems of maintaining the proper gap between the rotor and the side plates under varying load conditions, dimensional changes due to thermal expansion must also be taken into account during operation of the pump. In an attempt to overcome the foregoing problems, fluid pressure is uti lized to maintain the rotor in an axially floating condition between the side plates during operation of the pump. However, the pump shaft bearing and sealing assemblies rotationally supporting the rotor, must be such as to preserve the floating condition of the rotor despite the existence of rather substantial axial thrust loads and without imposing any substantial frictional resistance against rotation.

It is therefore a primary object of the present invention to provide a thrust absorbing bearing assembly for rotary vane types of pump units so as to isolate the pump rotor from external axial thrust loads and yet provide adequate rotational support for the rotor.

An additional object of the present invention is to provide in combination with the pump shaft bearing assemblies, balanced seal means which will adequately seal the bearing assemblies from the pump chamber and preserve the floating condition of the rotor under varying thermal conditions causing dimensional changes without imposing any substantial resistance to rotation of the rotor.

A still further object of the present invention is to provide a combined bearing and sealing assembly for pump shafts which may be easily assembled and disassembled for repair and replacement purposes as well as to accommodate the mounting of an axial thrust absorbing device on either axial side of the pump unit.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like 3,392,677 Patented July 16, 1968 numerals refer to like parts throughout, and in which:

FIGURE 1 is a side elevational view of a typical installation for a pump unit embodying the improvements of the present invention;

FIGURE 2 is a top plan view of the pump unit shown in FIGURE 1;

FIGURE 3 is a front elevational view of the pump unit shown in FIGURE 2;

FIGURE 4 is an enlarged partial sectional view taken substantially through a plane indicated by the section line 44 in FIGURE 2; and

FIGURE 5 is a partial sectional view taken substantially through a plane indicated by section line 5-5 in FIGURE 4.

Referring now to the drawings in detail, it will be observed that a pump unit generally denoted by reference numeral 10 which embodies the improvements of the present invention, is driven from some source of motive power 12 through a universal shaft coupling 14. In addition to the transfer of driving torque to the pump unit, substantially high axial thrust is usually applied by such drive arrangements.

As shown in FIGURES 2 and 3, the pump unit 10 is adapted to be coupled to the input source of power on either axial side by means of a thrust absorbing assembly 16 to which the universal shaft coupling 14 is connected. The thrust absorbing assembly 16 is therefore associated with one of the combined bearing and fluid sealing assemblies 18 which rotatably support the pump shaft 20 projecting axially from opposite ends of the pump housing 22, the pump housing having an inlet portion 24, an outlet portion 26 and a pressure regulating relief valve assembly 28 associated therewith. The pump housing 22 includes end sections 30 to which the combined bearing and fluid sealing assemblies 118 are connected. The thrust absorbing assembly 16 is therefore secured to the end section 30 of the housing on one side replacing the end cap 32 associated with the bearing and fluid sealing assembly 18 on the other side as shown in FIGURE 2.

Referring now to FIGURE 4, it will be observed that the housing section 30 encloses the combined bearing and fluid sealing assembly 18 on each axial side of the pump chamber enclosed by the side plates 34, the pump rotor 36 being keyed to the pump shaft 20 with proper axial clearance from the internal wall surface 38 of the side plates as hereinbefore indicated. The pump shaft 20 therefore includes an intermediate section 40 of maxi mum diameter to which the pump rotor 36 is keyed and progressively reducing diameter sections 42, 44, 46, 48 and 50 on opposite axial sides of the pump shaft. The thrust absorbing assembly 16 is splined to the minimum diameter shaft section 50 for rotation. therewith while the bearing and fluid sealing assembly 18 is mounted about the shaft sections 42, 44 and 46.

As ociated with the assembly 18 within the end section 30 of the pump housing is a seating wall formed by the annular element 52 positioned with radial clearance about the shaft section 44 and held in axially fixed position against the annular adapter plate 54 which abuts the radially inwardly projecting portion 56 of the end section 30 of the housing. O-ring elements 58 and 60 respectively seated between the adapter plate 54 and the annular element 52 and between the plate 54 and the housing section 30 seal the cavity 62 formed by the housing section 30. Fluid sealing means 64 is mounted on the shaft section 42 on one side of the annular seating element 52 axially spacing the roller bearing assembly 66 from the side plate 34.

The roller bearing assembly includes an inner race 68 press-fitted onto the shaft section 46 in abutting re- 3 lation to the shoulder formed between the shaft sections 44 and 46. The caged roller bearing elements 72 are removably mounted on the inner race element 68 together with the outer race 74 and the annular bearing housing 76 within which the outer race 74 is axially held by the retainer ring '78. The bearing housing is provided with a radial end groove 80 which receives the pin 82 projecting axially from the annular seating element 52 so as to prevent rotation thereof. An O-ring element 84 is also mounted about the shaft section 44 in axial engagement with the radial inner end of the bearing housing 76 so as to seal the roller bearing from any leakage of fluid that may enter the space between the seating wall and the bearing housing 76, this space being vented through the seal vent fitting 86 mounted by the housing end section 30.

The fluid sealing means 64 includes an annular sealing element 88 one axial end of which is in wiping engagement with the annular seating element 52. The other axial end portion of the sealing element 88 is rotatably supported on the shaft section 42 by the O-ring element 90 in sealing engagement with the shaft section 42. The O-ring element 90 is retained within the annular recess formed in the sealing element 88 by means of the annular retainer disk 92. The sealing element 88 is coupled to the shaft section 42 for rotation with the pump shaft. Toward this end, an annular spring holder element 94 is secured to the sealing element 88 by means of the groove 96. An annular ring 98 is coupled to the shaft section 42 by means of the annular sleeve 108 provided with a slot for receiving the head of a pin 112 projecting radially from the shaft section 42. As shown in FIGURE 5. The ring 98 is provided with circumferentially spaced tabs 100 received within slots 102 formed in the spring holder 94. The annular ring 98 will thereby accommodate axial adjustment in the spacing between the spring holder 94 and the spring retainer 104 between which the coil spring 106 is mounted. Also, a thrust washer element 114 is disposed between the spring retainer 104 and the shoulder 116 formed between the shaft sections 40 and 42. Accordingly, the coil spring 106 reacts between the pump shaft and the sealing element 88 rotatable therewith to thereby axially bias the sealing element 88 into wiping engagement with the annular seating element 52 in order to maintain the rotor 36 and the pump shaft to which it is connected in the axially floating condition aforementioned. Thus, it Will be apparent that the sealing means 64 on either side of the pump chamber will yieldably center the rotor despite dimensional changes caused by thermal expansion by exerting axial bias on the sealing elements 88 offering little frictional resistance to rotation as compared to any resistance resulting from seizure between the rotor 36 and the inner wall surfaces 38 of the side plates 34.

With continued reference to FIGURE 4, it will be appreciated that the roller bearing means 66 can only resist radial loading on the pump shaft. However, in view of the input drive arrangements with which the pump unit may be associated, as hereinbefore indicated in connection with FIGURE 1, a Substantial axial load on the pump shaft 20 must be avoided in order to prevent disturbance of the axial floating condition of the pump rotor. Accordingly, the thrust absorbing assembly 16 is designed to transfer rotatable torque to the pump shaft without any axial thrust. The thrust absorbing assembly is mounted on the housing by an end bearing cap 118 secured to the end section 30 by means of the fasteners 120 in order to enclose a ball-type of thrust bearing 122 and hold the bearing housing 76 of the roller bearing means 66 in axially assembled relation on the pump shaft. The small diameter end section 50 of the pump shaft is splined to a shaft extension 124 by means of the key element 126 so that torque is transmitted from the shaft extension to the pump shaft without transferring any axial thrust in view of the relative axial displacement permitted between the shaft extension and the pump shaft. The shaft extension is provided with an end splined portion 128 so that it may be rotatably connected to the input drive and a sleeve portion 130 which extends into the bearing cap 118 through an opening closed by the grease seal 132. The inner axial end of the sleeve portion 130 is provided with a flange 134 radially spaced from the bearing cap as well as being axially spaced from the roller bearing means 66 in order to avoid transfer of any axial thrust to the roller bearing means. The radially inner race 136 of the thrust bearing 122 is axially fixed on the sleeve portion 130 between the flange 134 and the thrust washer 138 while the radially outer race 140 of the thrust bearing is axially positioned between the bearing cap 118 and an annular thrust ring 142 received in an annular groove formed in the bearing cap in axial alignment with the flange 134. It will be also noted that the radially outer race 140 of the thrust bearing is axially positioned within the bearing cap with radial clearance 144 so as to avoid any radial loading of the thrust bearing 122. Instead, the thrust bearing 122 will exclusively transfer any axial thrust imposed on the shaft extension 124 to the pump housing by means of the bearing cap secured to the housing end section 30.

As the universal coupling 14 transmits driving torque to the pump shaft 20 through the shaft extension 124, the thrust applied thereto is resisted by the thrust bearing 122 and transmitted to the pump housing. Radial loading of the pump shaft on the other hand, is exclusively resisted by the roller bearing means 66 so that the pump rotor is isolated from the external thrust load and maintained in its axially floating condition, while dimensional variations due to thermal conditions are automatically compensated for by the balanced seal means 64 which prevent flow of leakage fluid from the pump chamber into the roller bearing means.

The operation of the bearing and sealing arrangement hereinbefore described should be apparent as well as its construction, assembly and installation. It will be appreciated that the thrust absorbing assembly 16 may be installed on either axial side of the pump unit. Assembly or replacement of the sealing means 64 is also facilitated since the roller elements 72 and bearing housing 76 of a the roller bearing 66 may be removed together with the seating wall formed by the element 52 and plate 54 in order to axially slide the parts of the sealing means 64 over the inner race 68 onto the shaft section 42. Thus, the outer diameter of the inner race 68 is equal to or less than the shaft section 44 and therefore less than the inner diameter of the rotatable sealing element 88 associated with the sealing means.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be restored to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. In a fluid displacing device having a housing, a power shaft extending through the housing, a pair of side plates fixed to the housing enclosing a fluid chamber therein and a rotor mounted on the shaft with axial clearance between said side plates, means for preserving an axially floating condition of the rotor despite dimensional variations in said axial clearance comprising a pair of radial bearings mounted by the housing and rotatably supporting the shaft on opposite axial sides of the rotor, thrust absorbing means slidably mounted by the shaft and engageable with the housing for transmitting torque to the shaft while isolated from any axial thrust, and seal means axially spacing the bearings and the thrust absorbing means from the side plates for preventing leakage flow of fluid through said side plates to the radial bearings and axially centering the shaft.

2. In combination with a pump housing and a rotor mounted therein on a pump shaft between a pair of side plates enclosing a pressure chamber from which the pump shaft extends, a pair of bearing assemblies mounted within said housing on opposite axial sides of the rotor for rotatably supporting the rotor and the pump shaft in an axially floating condition and thrust absorbing means mounted by the housing adjacent at least one of the hearing assemblies for exclusively transferring axial loads and driving torque to the pump housing and the pump shaft respectively, each of said bearing assemblies includ ing an annular bearing race received within the pump housing in coaxial relation to the pump shaft, a bearing cap secured to the pump housing in axially abutting relation to the bearing race, axially fixed wall means mounted within the housing for axially spacing the bearing race from the side plate, radial bearing means mounted on the pump shaft within the bearing race for resisting only radial loads and balanced seal means mounted on the pump shaft between the wall means and the side plate for preventing flow of leakage fluid from the pressure chamber to the radial bearing means.

3. The combination of claim 2 wherein said seal means includes a rotatable sealing element, means connecting the rotatable sealing element to the pump shaft for rotation therewith, and spring means reacting between the pump shaft and the rotatable element for axially biasing the sealing element into wiping engagement with the wall means to yieldably maintain axial clearance between the side plates and the rotor.

4. The combination of claim 3 wherein said thrust absorbing means comprises a shaft extension slidably keyed to the pump shaft and projecting into the bearing cap, thrust bearing means mounted in axially fixed relation on the shaft extension within the bearing cap, and means for holding the thrust bearing means axially fixed to and radially spaced from the bearing cap.

5. In combination with a fluid displacing device having a housing and a rotor mounted therein on a power shaft between a pair of side plates enclosing a pressure chamber from which the shaft extends, a pair of radial bearing assemblies supporting the rotor in a floating condition, fluid sealing means adjacent the side plates on opposie sides of the rotor for preventing leakage and yieldably holding the rotor in said floating condition and thrust absorbing means mounted by the housing adjacent to at least one of the bearing assemblies for isolating the shaft and rotor from axial loads while transmitting driving torque to the shaft.

6. The combination of claim 5 wherein said thrust absorbing means includes a bearing cap secured to the housing, a shaft extension slidably keyed to the shaft and projecting into the bearing cap, thrust bearing means mounted in axially fixed relation on the shaft extension within the bearing cap, and means for holding the thrust bearing mean-s axially fixed to and radially spaced from the bearing cap.

7. The combination of claim 5 wherein said sealing means comprises a seating wall axially fixed within the housing in abutment with each of the bearing assemblies, a rotatable sealing element, means connecting the rotatable sealing element to the shaft for rotation therewith, and spring means reacting between the shaft and the sealing element for axially biasing the sealing element into wiping engagement with the seating wall to yieldably maintain axial clearance between the side plates and the rotor.

References Cited UNITED STATES PATENTS 1,673,259 6/1928 Meston et al. 103-126 1,963,705 6/1934 Kasch 103126 2,105,428 1/1938 Maglott 103126 2,316,565 4/1943 Collier 103-126 2,593,369 4/1952 Wachter 103-126 2,746,394 5/1956 Dolza et a1. 103-126 2,758,548 8/1956 Rockwell 103-126 2,848,952 8/1958 Wakeman 103-126 2,878,757 3/1959 Marco 103-426 3,063,378 11/1962 Hart 103-126 3,083,645 4/1963 Donner et a1 103-426 FRED C. MATTERN, JR., Primary Examiner.

W. I. GOODLIN, Assistant Examiner. 

